That's certainly a factor.
Another possible factor is that the author of the remastered MD5 models is Capnbubs, who started doing those models in 2013 Link
. The skin of the grunt in the remaster is exactly the same, with an added muzzleflash, and the dog skin is 100% the same.
Back then Capnbubs already mentioned working with an skeletal model format, which may be the MD5 format itself. I don't know when the IQM format was created.